The present invention relates to a new and distinct cultivar of chrysanthemum plant, botanically known as Chrysanthemum×morifolium Ramat., and hereinafter referred to by the cultivar denomination ‘Zanmuspen’. ‘Zanmuspen’ is a product of a breeding and selection program for outdoor pot mums (garden mums) which had the objective of creating new chrysanthemum cultivars with a double type infloresence, a natural season flower date starting at August 25–30; blooming for a period of 5 weeks. ‘Zanmuspen’ is a seedling resulting from the crossing of the female parent id 2862 and male parent id 3052. Plants of ‘Zanmuspen’ differ from plants of the female parent in the color of ray-florets: yellow in the female parent and white in the seedling. Plants of ‘Zanmuspen’ differ from plants of the male parent in the natural season blooming period; those of the seedling flower 1–2 weeks earlier.
The new and distinct cultivar was discovered and selected as a flowering plant by Wilhelmus Bernardus Blom on a cultivated field in Rijsenhout, The Netherlands in 2005. The first act of asexual production of ‘Zanmuspen’ was accomplished when vegetative cuttings were used from the initial selection in 2005 and propagated further in a controlled environment in Rijsenhout, The Netherlands. The new cultivar has been found to retain its distinctive characteristics through successive propagations.